General Flooded petrol engine

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General Flooded petrol engine

David Bliss

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* About 10 years ago I bought a Seicento and after about 20 000 miles had an odd thing happen. I had driven through a lot of heavy rain and decided to let the car dry outside before putting it in the garage. Later I started and drove it the few yards into the garage, the next day the engine would not start immediately and when it did it was definitely flooded, there were clouds of black smoke from the exhaust. At the time I just thought it was a one-off occurrence, but since then it happened several times, always after the car had been run briefly (seconds) from cold and then stopped and left and for more than 12 hours. Once I realized this I would always run the car down the road to get it hot before garaging it which prevented the problem happening again.

My daughter also has a Seicento and I warned her that if she needed to move her car a small amount to be sure to run the engine until it was hot before turning the ignition off. On one occasion she forgot and later the engine would not turn over, one cylinder had filled completely with petrol and had hydrauliced, stopping the engine from turning. Luckily I knew what the problem was and how to deal with it - by removing the plugs and spinning the engine over to expel the excess petrol I was able to sort things out without causing any damage to the engine. I talked to someone from our local garage about it and was told they had seen this problem at least three times on various Fiats and in all cases the engines had been badly damaged.

The other day the same happened to my Panda Active. I assume that, with age, in certain circumstances and on rare occasions, an injector will stick and with slight gas pressure from the fuel tank can flood one or more cylinders. When the injectors are hot they are unlikely to stick, so you should always run the engine long enough to get it hot. I do not know whether putting the occasional injector cleaning treatment through the system would alleviate the problem or not, but having lived with the weird problem for around 10 years I know how to avoid it so haven’t tried this cleaning treatment I just take the necessary precautions.


Has anyone else encountered this phenomenon? I haven’t seen it mentioned in other posts.
 
Yep, happened on our idea a little while back, it is very rare for me to start the engine and not run it so hasn't happened regularly.
The engine could crank but not fire. Can't remember the time frame but I went out to sort it out, used the starter to get the car onto the drive (must weigh double a Sei!) And they gave it another crank.
There was a hint of a fire so I cranked it plenty and it eventually went with no more work needed. Started with a miss and plenty of smoke.

It happened on the people over the roads clio, I only noticed when the AA had turned up. Again, plenty of cranking and smoke.
 
My Panda once threw it's toys out of the Pram and was a pig to start, this was after being started when cold, and then stopped very shortly thereafter.

I now make sure I don't make that mistake :)


Trev
 
My Panda once threw it's toys out of the Pram and was a pig to start, this was after being started when cold, and then stopped very shortly thereafter.

I've seen something similar on the 500 - most likely down to the injection system overfuelling & flooding the engine.
 
I've seen something similar on the 500 - most likely down to the injection system overfuelling & flooding the engine.

Yes, me too , thought it should have stopped with the advent of fuel injected engines , but apparently not..!!,
Big difference between a "flooded " engine being too rich to burn / fire , and it actualy hydraulically locking though..!!
 
I have gone through several ‘procedures’ to try to resolve the problem. Someone suggested that when the engine was started from cold and switched off almost immediately that, the next time the engine was started, it would be overfueled because there would be wet fuel left in the engine from the previous time so the system would perform a cold start on an already wet engine. This would cause a very rough start. To test this idea I tried running the engine for at least a couple of minutes at moderate revs then giving it a rev or two with the throttle full open before switching off. The next start still exhibited the flooded symptoms, so that theory was incorrect.
I had once had my Seicento engine mildly lock (hesitating for split second before that cylinder managed to turn), but my daughter’s Seicento locked solid so it was necessary remove the plugs and I pushed the car out of the garage in gear to turn it over. In the eight years since she has not had a repeat of the problem as she now knows to always allow the engine to run until it has come up to normal temperature.

If this problem does occur is important not to rev the engine when it does start but to allow it to idle for a few minutes. My local garage told me that they had known of several cases where people had reved the engines and caused damage to the cylinder and piston as the petrol had washed all the oil off. They said it was a very rare occurrence where an injector stuck and there was slight back pressure in the petrol tank, probably caused by temperature change.
 
Defiantly Sounds like injector leak-by, where there is a bit of muck on the injector seat or plunger so it doesn't shut off and empty's the remaining fuel pressure into the engine. Make sure you add Fuel system treatment/cleaner every service to stop this happening, also removes varnish that causes sticky injectors.
Or if it's getting a real problem change the injectors, because prolonged leak-by can cause "bore wash" and age the engine dramatically!
Leak-by is an easy test, by the use of a fuel pressure test gauge or sometimes you can unbolt the whole rail, turn the ignition on so it primes then turn it off and watch to see if any injectors drip, but the gauge test is more accurate and safer,most garages can do it.
Just be sure to drop it off night before and let them do it cold next morning.
 
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